JPS6132627A - Mobile communication control system - Google Patents

Abstract

PURPOSE:To secure a communication route from a base station to a mobile station all the time by providing the mobile station with plural reception systems and using plural reception systems during channel switching. CONSTITUTION:A transmission part 10 and a reception part 11(RX1) or 12(RX2) are used during a call. This reception part varies the output frequency of a frequency syntheriser 24 under the command of a control part 26 and receives a radio wave of one optional radio frequency among radio waves sent from the base station. If the mobile station receives a speech signal of frequency fO1 during channel switching, a channel switching request and a switching destination channel number (frequency fN) are sent to the mobile station by using an out- band control signal (SVO) from the base station. Further, the base station sends a radio section continuity signal (RLP) of frequency fN1 to the mobile station so as to test the normalcy of a switching destination channel (fN). The normal station when receives the switching destination channel number (fN) with SVO of the channel of frequency fO1 places the receiver (RX2) which is not used so far in a reception state and sets it as the switching destination channel to wait for down RLP.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a multi-channel access mobile communication system in which a mobile station switches between multiple radio channels. This invention relates to a control method for channel switching during a call.

[Conventional technology]

In order to accommodate a large number of subscribers while making effective use of radio frequencies4, Hibiki's mobile communication system uses mobile stations that allow multi-channel access, and provides services by repeating small wireless zones. Often constitutes an area.

FIG. 1 is a diagram showing an example of the configuration of a mobile communication system based on a small wireless zone configuration, and shows a case where a service zone is configured with three small wireless zones, and 1, 2, and 3 respectively indicate the Oguma line. It represents the zone. A base station 4.5.6 is placed in each small radio zone, and communicates with mobile stations within its own radio zone using a preset radio frequency. The radio frequencies that can be used in each of the radio zones 1 to 3 are different in order to prevent radio wave interference. 7 is a mobile station located within the wireless zone 1, so when a call is made, a call line is set up between the mobile station and the base station 4.

When the mobile station 7 crosses the zone boundary and moves into the wireless zone 2 while making a call, a new channel with a radio frequency different from the old communication channel is created between the mobile station 7 and the base station 5. The new wireless channel is set up as a communication path, and the call is made using the new wireless channel.

In such a mobile communication system, it is assumed that the mobile station has the ability to select any channel from preset communication channels (multi-channel access system).

When the mobile station moves from zone 1 to zone 2 in FIG. 1, it is necessary to switch the busy channel as described above, and this is normally done in the following steps.

■ Cuts off the downlink (from base station to mobile station) audio signal during a call and sends a new channel designation signal.

■ The mobile station moves to a new channel and starts receiving on the new channel (in this state, the mobile station communication path is disconnected). The new wireless base station transmits a wireless link signal on the new channel.

■ The mobile station that has received the downlink radio section guidance signal on the new channel transmits an uplink radio section guidance signal to the base station.

■ When the base station receives an uplink radio section conduction signal, it cuts off the transmission of the downlink radio section conduction signal and opens a communication path. When the mobile station detects that the downlink wireless communication signal is disconnected, the uplink wireless communication signal is disconnected and the communication path is resumed.

■ If the mobile station cannot receive the downlink radio section communication signal after switching to the new channel, the mobile station returns to the old radio channel and resumes the call. In the case of radio wave interruption on the old radio channel, the mobile station starts a call termination operation. In addition, the new channel transition Hua,
If the base station is unable to receive the uplink radio section transmission signal, it also moves to a call termination operation.

[Problem to be Solved by the Invention 3] In the conventional channel switching process during a call accompanying a wireless zone transition as described above, if the wireless section conduction signal cannot be correctly received both up and down after transition to a new channel, , there was a problem in that the call was forced to end because there was no way to communicate the next action. In actual systems, cases like this occur quite often.

The above is a case of channel switching during a call due to wireless zone transition, but the operation of the mobile station is exactly the same even when changing channels within the same wireless zone, and there are problems similar to those described above.

In order to eliminate these drawbacks, the present invention provides a mobile station with multiple receiving systems and uses the multiple receiving systems when switching channels to always ensure a communication path from the base station to the mobile station. It is.

Hereinafter, the structure and operation of the present invention will be explained in detail using drawings of embodiments.

〔Example〕

FIG. 2 is a block diagram showing an example of the basic configuration of a mobile station that implements the present invention, in which 8 is a transmitting and receiving antenna, 9 is a receiving antenna, 10 is a transmitter (hereinafter also referred to as TX), and 11 is a mobile station. receiving section (hereinafter also referred to as RXI); 12 is a second receiving section (hereinafter also referred to as RX2); 13 is a handset; 1
4 represents a switch for selecting either RX1 or RX2.

During a call, either the transmitter 10 or the receiver 11 or 12 is used. Turn off the power to the receiver that is not in use. The configurations of the transmitter and receiver may be arbitrary as long as they can transmit and receive the required radio waves.

FIG. 3 shows the configuration of a typical receiving section.

FIG. 3 is a diagram showing either the receiving section 11 or 12 in FIG. 2, where 15 is a received signal input terminal, 16 is a band pass filter, 17 is a first reception mixer, and 18 is a band pass filter. , 19 is a second reception mixer, 20 is an intermediate frequency amplifier, 21 is a demodulator, 22 is an audio signal amplifier, 23 is an audio signal output terminal, 24 is a frequency synthesizer, 25 is a crystal oscillator, and 26 is a control section.

Such a receiving section changes the output frequency of the frequency synthesizer 24 according to a command from the control section 26, and receives any one radio frequency among the radio waves transmitted from the base station.

In the method of the present invention, it is necessary for the mobile station to have two receiving sections, but the two branches of the post-detection selection guide, which is often used in mobile communications, can be used as separate receiving systems only when switching channels. is also possible.

However, in this case, it is necessary to set the reception frequencies of the two reception systems separately, so two frequency synthesizers are required.

Two receivers capable of selection ubiquity after detection are installed.
FIG. 4 shows the configuration when used as one receiving system.

FIG. 4 shows a mobile station consisting of a post-detection selection ubiquitous receiver consisting of two branches and a transmitter, in which 8 is a transmitting and receiving antenna, 9 is a receiving antenna, 10 is a transmitter, 13 is a handset, and 26 is a control unit. , 27 is the first receiving branch, 2
8 is a second receiving branch, and 27 and 28 each include a demodulator. Further, 29 is a first frequency synthesizer, 30 is a second frequency synthesizer, 31 is an intermediate frequency output level comparison circuit, 32 is a first audio switch, 3
3 is a second audio switch, 34 is a first control signal switch, 35 is a second control signal switch, 36 is a first frequency synthesizer switch, 37 is a second frequency synthesizer switch, and 38 is a switch for a second frequency synthesizer. The third frequency synthesizer switch 39 is a fourth frequency synthesizer switch.

In normal diversity mode, switches 36.38 are ON and switches 37.39 are OFF (or vice versa), and the two gear punch branches 27 and 28 are connected to the synthesizer 2.
The same local oscillator signal is supplied from 9 (or 30).

Switches 32, 33, 34, and 35 are level comparison circuits 31
As the higher level branch is selected by the command, 32.34 turns ON.

33.35 is OFF or 32.34 is OFF.

Either 33.35 is ON.

On the other hand, the switch control during channel switching is as follows.

Here, the first receiving branch 27 has a higher output;
Assume that this branch is selected by level comparison circuit 31. It is also assumed that synthesizer 29 is used.

In this case, the switch 36 is turned off, the switches 35 and 37 are turned on, and the local oscillation signal of the switching destination channel is supplied from the synthesizer 30 (the switch 38 is turned on, and the switch 39 is turned on).
It's a FF book. Naturally, the receiving branch 1 is supplied with the local signal for the channel before switching. ).

Further, 32 and 34 are up to *ON, and 33 remains OFF. In this state, when a signal on the switching destination channel is received from the antenna 9 and it becomes possible to talk on the switching destination channel, the switch 33 is turned ON and 32.34 is turned OFF.
FF.

Thereafter, when the switch 38 is turned OFF and the switch 39 is turned ON, the receiving branch 1 also becomes able to receive the switching destination channel frequency, and enters the normal diversity mode.During one or more channel switching operations, the level comparison circuit 31 stops its operation. .

As described above, if there are two frequency synthesizers, the two branches of the diversity receiver can be used independently and used as two receivers when switching channels.

Next, a channel switching procedure according to the present invention will be explained.

When a mobile station moves from a small wireless zone to a new wireless zone base station, a new communication channel is generally set in the dark with the new wireless zone base station, but for the purpose of eliminating co-channel interference etc. In some cases, channel switching is performed.

The following algorithm can of course be used in both cases.

For ease of explanation, the old radio channel frequency is fo
, the new (switching destination) radio channel frequency is f, and downlink and uplink are distinguished by subscripts 1 and 2. That is, the old channel is fmi, the old channel is fg, and the new channel is fI! 11 New channel upstream is f2.

There are two methods of transmitting the control signal specifying the switching destination channel: a method that uses an out-of-audio band control signal, and a method that temporarily cuts off the audio signal and transmits the control signal.

Conventionally, the latter of the above methods has been used, but by adopting the former method, the momentary interruption time of the audio signal can be shortened. Since the control procedure is the same for both methods, we will first explain the case where the control signal ends with the use of an out-of-audio band control signal.

The audio out-of-band control signal used for channel designation is a control signal 41 that is transmitted simultaneously with the audio signal 40 in the lower frequency band of the audio signal 40 band-limited from frequency fa to fb as shown in FIG. It is.

Channel switching is performed based on the algorithm described below.

■ The mobile station is receiving an audio signal at frequency f9 (
It is assumed that the receiver is RXI. ). The base station notifies the mobile station of a channel switching request and the switching destination channel number (frequency fN) using an fb out-of-band control signal (hereinafter abbreviated as SVO).

Also, on the base station side, the line connection with the fixed upper station is completed at this point. Furthermore, the base station switches to the switching destination channel (f
To test that N) is normal, the frequency f,!
A downlink radio link signal (hereinafter referred to as RLP) is sent to the mobile station at
(abbreviated as ) (in the case of channel switching accompanying zone transition, the RLP signal is transmitted from the base station of the transition destination zone).

■ When the mobile station receives the switching destination channel number (f N ) on the SVO of the channel with frequency f: 5, it puts the previously unused receiving 1ll (RX2) into the receiving state.
Set as the switching destination channel and wait for downlink RLP.
At this time, the old channel (RXI) remains in the communication state.

■ When the mobile station receives 1) RLP on RX2, it turns off the audio switch on the input side of the transmitter, switches to frequency transmission, and sends out the 1) RLP signal. f: 4 receiving system (R
After sending the upper QRLP signal, X2) waits for the downstream RLP (IF signal) to become a receiving station.

■ When the base station receives the uplink RLP signal from the mobile station, it turns on the downlink audio switch through the RLP signal output port.
N and transmits the audio signal from the upper fixed station.

■ When the mobile station detects the interruption of the downlink RLP signal from the base station, it turns on the uplink RLP signal transmission port and the uplink (transmission 8) audio switch. Turn on the audio switch of the receiver receiving the f3 signal, and turn off the audio switch of the receiver receiving the f3 signal.After that, the receiver that was receiving the f3 signal stops functioning.

■ After confirming the upstream RLP signal reception point by fb, the base station turns on the upstream audio switch. More fb
Stop transmitting and receiving on fg, and release f5 as the transceiver that was involved in transmitting and receiving the bow, and the fixed line that is no longer needed.

The above is the algorithm when the signal is sent and received correctly, but if the signal cannot be received midway, the following steps are taken.

Even though the mobile station received the channel switching request and the switching destination channel (f!, ) on RXI in the above ■, R
If the mobile station cannot receive the downlink RLP signal within the specified time at
Notify the base station that RLP decoding has not been received and wait for another instruction. If no further instructions are given within a certain period of time, transmission and reception using fA and f2 will continue as before.

If the base station is unable to receive the upstream RLP signal within the specified time in (2) above, the base station once again notifies the mobile station of the channel switching request and the switching destination channel number using SVO f9. Even if you repeat this operation a specified number of times, RLP will not work on the new channel.
When signals cannot be exchanged, channel switching is stopped (a channel switching stop signal is sent to the mobile station).

After the base station stops transmitting the downlink RLP signal in step ① above, if the R, L, P signal is received even after the specified time has elapsed (the mobile station is in an abnormal state), the mobile station will continue to move based on f-count. Commands the station to cancel channel switching.

The above explanation is for the case where the audio out-of-band control No. 41 is used, but when the audio signal is temporarily interrupted and the control signal is transmitted as in the conventional system, the audio out-of-band control signal can also be used in °I. It is almost the same as the method used above.

That is, the channel switching algorithm at this time is as follows.

■ The mobile station is receiving an audio signal at frequency f9 (
The receiver is assumed to be RXI). The base station cuts off the downlink audio signal and notifies the mobile station of a control signal (channel switching request and switching destination channel number (frequency f, J)). Also, on the base station side, the line connection with the fixed-side upper station is completed at this time. The base station also uses the switching destination channel (fN).
The RLP signal is sent downstream.

■ When the mobile station reads the switching destination channel number (fN) from the control signal that interrupts the audio signal of the channel with frequency fmi, it receives the previously unused received tl! (RX
2) as the receiving state and set it as the switching destination channel,
Bottom 1) Wait for RLP signal. At this time, the old channel (
RXI) remains in the receiving state. However, the downlink audio signal is cut off during the time period when the downlink control signal is sent.

The following steps are the same as those in (1) to (4) in the case of using an out-of-audio band control signal. If the signal transmission and reception is not performed correctly, the following operation is performed.

Even though the mobile station received the channel switching request and the switching destination channel (f-) on RXI in above (■), RX2(
F,! , ), the mobile station waits for another instruction from the base station at f5 if the downlink RLP signal cannot be received within the specified time.

Or report non-reception of RLP if you are deaf.

If the base station is unable to receive the RLP signal (1) above within the specified time in (■) above, the base station once again notifies the channel switching request and switching destination channel number using the control signal that is inserted into the audio signal using fg. do. If you cannot send or receive RLP signals on the new channel even after repeating this operation a specified number of times,
Stop channel switching.

1) If the RLP signal is received even after the specified time has passed after the base station has stopped transmitting the RLP signal in step 1 above (1)
This state is an abnormal state of the mobile station. ) commands the mobile station to cancel channel switching at fA.

The above explanation describes the case where the mobile station has two independent receivers, but if the mobile station is a multicast receiver, the multicast reception will be stopped when a channel switching request is made. Then, the two diversity branches can be used as separate receivers, and after channel switching is completed, the system can return to the diversity reception mode.

〔Effect of the invention〕

As explained in detail above, according to the method of the present invention, communication is always possible on the old channel downlink even during channel switching, so even if signal transmission and reception are not performed normally,
There is an advantage that the next operation can be notified to the mobile station.

Previously, this method was not available, so there were many cases where calls were forced to end while switching channels.

The present invention also has the advantage of being able to shorten the audio interruption time that occurs due to channel switching. The shortening effect is that the control signal is sent by cutting off the audio signal.
Alternatively, the out-of-band control signal can be transmitted during a call, but in the latter case in particular, after the mobile station receives a channel switching request and the switching destination channel number,
1) If the RLP signal cannot be received on the new channel, the base station can be notified of the non-reception of the downlink RLP signal using the upstream out-of-band control signal on the old channel, so there will be no momentary interruptions in call audio. Furthermore, according to the present invention, since it is possible to continue talking on the old channel until the downlink RLP signal is received on the new channel, the channel switching time can be shortened by this amount (after the downlink RLP signal is received, the downlink audio signal remains unchanged). Although it can be received on the old channel, the transmitted audio will be temporarily interrupted because the transmitter Mlf1 will switch to the new channel). Furthermore, regarding the opening/closing times of the downlink audio switches on the base station side and the mobile station side, first the downlink switch of the new channel is turned ON, and after a certain period of time, the downlink switch of the old channel is turned OFF and F, resulting in a momentary interruption of downlink audio. It is also possible to make it zero.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of a mobile communication system with a small wireless zone configuration, FIG. 2 is a block diagram showing an example of the basic configuration of a mobile station implementing the present invention, and FIG. 3 is a typical receiver. FIG. 4 is a block diagram showing a configuration when a receiver capable of selection ubiquity after detection is used as two receiving systems. Figure J5 is an explanatory diagram of the out-of-audio band control signal. 1.2.3...Small wireless zone, 4,5.6
... Base station, 7 ... Mobile station, 8
... antenna for transmitting and receiving, 9 ... antenna for reception only, 10 ... transmitter, 11 ......
・First receiving section, 12...Second receiving section, 1
3...Handset, 14...Switch, 15...Received signal input terminal, 16...
...band pass filter, 17... first reception mixer, 18... band pass filter, 19.
...Second reception mixer, 20 ...Intermediate frequency amplifier, 21 ...Demodulator, 22 - Old -
・Audio signal j1@device, 23...Audio signal output layer, 24...Frequency walk synthesizer, 25.
Old...Crystal oscillator, 26...Control unit, 27
・・・・・・First receiving branch, 28 ・・・・・・
2nd reception processor, 29...first frequency synthesizer, 30.old...second frequency synthesizer,
31...Intermediate frequency output power level comparison circuit, 32
・・・・・・First voice switch, 33 ・・・・・・
Second audio switch, 34...Switch for first control signal, 36...Switch for first frequency synthesizer, 37...Switch for second frequency synthesizer Switch, 38 towns. Third frequency synthesizer switch, 39...
・Fourth frequency synthesizer switch, 4°...
...Audio signal, 41...Audio out-of-band control signal agent Patent attorney Takashi Honma Figure 1 Figure 2 Figure 3 Figure! i diagram

Claims (1)

[Claims] When a mobile station has a function of switching between multiple wireless channels and receives a channel switching command sent from a wireless base station during a call on a certain wireless channel,
In mobile communication systems that switch to another radio channel and continue a call, a mobile station is provided with multiple receiving systems, and normally at least one of the multiple receiving systems is used to make a call and switch channels. Sometimes, while capturing the receiving system in use, a call test is performed using another unused receiving system on the switching destination wireless channel specified by the wireless base station, and the call test results are confirmed to be good. A mobile communication control system characterized in that after confirmation, a call is started on the wireless channel.